Jest vs SuperTest: What are the differences?

Jest and SuperTest are both popular testing frameworks in JavaScript, but they serve different purposes and have distinct features. Let's explore the key differences between them.

1. Testing Environment: Jest provides a full-featured testing environment out of the box, allowing you to write and run tests without the need for any additional setup or libraries. On the other hand, SuperTest is a library specifically designed for testing HTTP servers or APIs.

2. Assertion Library: Jest comes with its own built-in assertion library and provides a wide range of built-in matchers, making it easy to write assertions in your test cases. SuperTest, being more focused on API testing, does not provide an assertion library. Instead, it integrates well with popular assertion libraries like Chai, allowing you to use your preferred assertion style.

3. Mocking Capabilities: Jest has powerful mocking capabilities built into its framework, allowing you to easily mock dependencies and external modules. It provides a simple API for creating and managing mocks, spying on function calls, and controlling their behavior during the test. Unlike Jest, SuperTest does not have built-in mocking capabilities.

4. Code Coverage: Jest provides built-in code coverage analysis, which allows you to track the percentage of your code that is covered by tests. It generates code coverage reports that help you identify areas of your codebase that need better test coverage. SuperTest, being focused on API testing, does not offer built-in code coverage functionality.

5. Async Testing: Jest has excellent support for testing asynchronous code, including promises, async/await, and callbacks. It provides built-in utilities to handle async operations, such as async/await syntax for cleaner and more readable tests. In comparison, SuperTest is primarily aimed at testing synchronous code and does not have built-in support for handling async operations.

6. Test Runner: Jest comes with its own test runner, which means you can run your tests directly from the command line using the jest command. It provides a built-in watch mode that automatically re-runs tests when files change. SuperTest, being a library rather than a standalone framework, does not provide a test runner. You need to use a separate test runner like Mocha or Jasmine to execute tests written using SuperTest.

In summary, Jest provides a full-featured testing environment with built-in mocking and code coverage support, while SuperTest is focused on API testing and integrates with external assertion libraries.